5 public questions tagged with this topic.
The association is a lichen. The algal phycobiont prepares food, while the fungal mycobiont provides shelter and absorbs water and minerals. Because lichens do not grow in polluted areas, they indicate air pollution.
Ref: NCERT Class 11 Biology Chapter 2: Biological Classification Bacteria - Structure and Economic Importance
The organism is a lichen, a mutually beneficial association between an algal phycobiont and a fungal mycobiont. The alga prepares food, while the fungus provides shelter and absorbs water and minerals. Lichens do not grow in polluted areas and therefore act as pollution indicators.
Ref: NCERT Class 11 Biology Chapter 2: Biological Classification Bacteria - Structure and Economic Importance
“Habitat destruction and pollution” for aquatic species, such as mollusks, are most threatened by. This relationship follows from the ecological mechanism represented by the terms in the item, not merely from an association between their names. Extinction risk rises when abundance, geographic range, or genetic variation becomes small because demographic chance, environmental fluctuations, inbreeding, and rare catastrophes then have disproportionate effects. Correlated losses among subpopulations further weaken regional persistence. The remaining alternatives—“Parasitism”, “Introduced predators”, “Hunting”—refer to different states, processes, or scales and therefore do not express the same causal relationship. The mechanism should be evaluated across both local and global scales. Local disappearance can be reversed by recolonization, whereas global extinction is irreversible and requires the loss of every surviving population. Field observations could test this account by measuring the proposed driver and the demographic or ecosystem response while controlling plausible confounding factors. This distinction matters because similar surface patterns can arise through different mechanisms, whereas ecological prediction depends on identifying the mechanism that actually changes rates.
Ref: Conservation Biology, Primack & Sher, 6th Ed., Ch. 7
Detection of microplastics in fish and shellfish provides a credible human-exposure pathway because these organisms are eaten, sometimes whole. The observation establishes potential dietary contact, although it does not by itself quantify absorbed dose or prove a particular disease. Risk assessment must distinguish particle presence in gut contents from edible tissues and consider particle size, additives, preparation, consumption rate, and toxicological evidence. Laboratory effects must be interpreted alongside environmentally realistic concentrations, while field detection demonstrates exposure but does not alone prove causation. Prevention requires reducing unnecessary plastic use, improving collection and recycling, controlling lost fishing gear, and limiting releases of fibres and tyre-wear particles. Because conventional polymers persist, fragmentation redistributes plastic into smaller pieces rather than removing its mass from the ecosystem. Trophic transfer can occur when predators consume contaminated prey, although evidence for consistent biomagnification of particle numbers remains system-dependent. Standardised sampling and contamination controls are essential because airborne fibres can enter samples during collection and laboratory processing.
Ref: Campbell Biology, Urry et al., 12th Ed., Unit 8 Ecology
Rain at pH 4.3 is strongly acidic relative to normal rain, whose pH is near 5.6 because of dissolved carbon dioxide. Since pH is logarithmic, pH 4.3 has about twenty times the hydrogen-ion activity of pH 5.6. Values of 6 or 5.5 are near or only slightly below natural rain acidity, while 7.2 is mildly alkaline. Sound classification links the source, atmospheric fate, exposure route, and mechanism of toxicity rather than relying only on the pollutant's name. Effective management combines cleaner fuels, emission standards, monitoring, urban planning, and protection of populations with high exposure or physiological vulnerability. The distinction is ecologically important because emission control must target either the directly released precursor or the product formed after atmospheric transport and reaction. Exposure depends on concentration, duration, ventilation, weather, and individual susceptibility, so a pollutant's presence alone does not fully predict biological harm. Atmospheric inversions can trap contaminants near the surface, while wind, turbulence, precipitation, and chemical transformation determine their eventual distribution and removal.
Ref: Campbell Biology, Urry et al., 12th Ed., Unit 8 Ecology
